Characterization of hot deformation behavior of a Ni-base superalloy using processing map

The hot deformation characteristics of a Ni-base superalloy are studied in the temperature range 1000-1200 degrees C and strain rate range 0.001-1.0 s(-1) using hot compression tests. Processing maps for hot working are developed on the basis of the variations of efficiency of power dissipation with temperature and strain rate. Hot deformation equation is given to characterize the dependence of peak stress on the temperature and strain rate. And hot deformation apparent activation energy of the Ni-base superalloy is about 493 kJ/mol. The power dissipation map reveals that a domain of dynamic recrystallization (DRX) exists in the temperature range of 1100-1150 degrees C and strain rate range of 0.01-0.001 s(-1), with its peak efficiency of 56% at about 11 25 degrees C and 0.001 s(-1), which are the optimum hot working parameters. Analysis of the flow behavior and microstructure observations indicated that dynamic recrystallization occurred at higher temperatures and lower strain rates. (C) 2008 Elsevier Ltd. All rights reserved.